Drill steel centralizer for coal drill



Apfil 9, 1957 R. F. HALE 2,788,194 DRILL STEEL CENTRALIZER FOR COAL DRILL Filed Dec. 24, 1952 2 Sheets-Sheet l INVENTORZ RALPH E H ALE ATTQRNEY April 9, 1957 R. F. HALE DRILL STEEL CENTRALIZER FOR COAL DRILL Filed Dec. 24,. 1952 2 Sheets-Sheet 2 INVENT-ORZ RA PH E HALE ATTORNEY Suited States DRILL STEEL CENTRALIZER FOR COAL DRILL Application December 24, 1952, Serial No. 327,846 7 Claims. (Cl. 255-51) This invention relates to drilling apparatus and more particularly to an improved centralizer for the drilling implement of a rotary coal drill.

In rotary coal drills of known types a drilling imple ment such as an auger drill steel is ofttimes driven by a motor which is guided for movement along an elongated guide frame, and the guide frame carries at its forward end a guiding means or centralizer for the auger steel for centering the drill bit with respect to the work during the starting of the drilling operation. Such centralizer means for the auger drill steel sometimes includes a slidable intermediate guide or centralizer for centering the intermediate portion of the drill steel to reduce the lateral vibration or whipping of the latter, and as the drilling tool is advanced after starting of the hole this intermediate centralizer or guide is shoved forwardly by the drilling tool to its foremost position on the guide frame in adjacency to or in engagement with the front centralizer for the steel. When the drilling tool is retracted along the guide frame this intermediate centralizer or guide is usually retracted or repositioned by hand, and the present invention contemplates improvements over such known drills in that when the feed for retracting the drilling tool is reversed an element of the feeding means engages the intermediate centralizer and automatically moves it rearwardly along the guide frame back to its initial intermediate position.

An object of this invention is to provide an improved drilling apparatus. Another object is to provide an improved centralizer or guiding means for the drilling implement of a drilling tool for reducing the lateral vibration or whipping of the steel during the drilling operation. Yet another object is to provide an improved coal drilling apparatus of the rotary auger type having feeding means for moving the drilling tool back and forth along a guide frame, and an intermediate centralizer or guide for the auger steel and wherein an element of the drill feeding means may effect movement of the intermediate centralizer or guide in one direction along the guide frame. Still another object is to provide an improved drill steel centralizer guided for sliding movement on the guide frame for the drilling tool and having improved means for retracting the centralizer from its forward position on the guide frame during retraction of the drilling tool. A further object is to provide an improved intermediate centralizer for the drill steel of a drilling tool of the type which is fed along a guide frame by a feed chain, and the latter has a projection which engages a lug on the intermediate centralizer or guide to retract the latter along the guide frame as the drilling tool is fed rearwardly. A still further object is to provide an improved automatically retractable centralizer for the drilling implement of a rotary coal drill. These and other objects and advantages of the invention will, however, hereinafter more fully appear.

In the accompanying drawings there is shown for purposes of illustration one form which the invention may assume in practice.

In these drawings:

.Fig. l is a plan view of a drilling apparatus in which ice an illustrative embodiment of the invention is incorporated.

Fig. 2 is a central longitudinal vertical section taken on line 2-2 of Fig. 1, illustrating the intermediate drill steel centralizer and its associated retracting means.

Figs. 3 and 4 are fragmentary sectional views taken on the plane of Fig. 2, showing the intermediate steel centralizer in different positions.

Fig. 5 is an enlarged cross section taken on line 5-5 of Fig. 2.

Fig. 6 is an enlarged detail horizontal section taken on line 6-6 of Fig. 2.

The drilling apparatus in which the present invention is embodied generally comprises an elongated guide frame 1 including parallel tubular guides or guide rods 2 rigidly connected at their ends by transverse frames 3 and 4 mounted on a longitudinal supporting frame 5, the latter in turn being supported in any suitable manner. A cross frame 6 is slidably guided on the parallel guides 2 for movement longitudinally of the guide frame and carries a gear housing 7 containing intermeshing spur gears 8 and 9, and a conventional motor 10 is mounted rearwardly on the gear housing for driving these gears. The spur gear 9 is keyed to a coaxial shaft 11 suitably journaled within the gear housing and which has a socket 12 for receiving the shank of an elongated drilling implement 13, herein desirably a conventional auger drill steel. A.

cross bolt 14 passes through registering openings in the shaft 11 and the steel shank for securing the latter in the shaft-socket. The auger steel has usual spiral vanes or flights 15 and extends longitudinally centrally between the parallel guides and has secured to its outer end a conventional rotary drill bit 16. Secured to the front transverse frame 4 is a centralizer bushing 17 through which the auger steel extends and this bushing serves to guide or center the drill bit during starting of a hole.

The supporting frame 5 carries a conventional reversible motor 2%) which drives, through conventional speed reducing gearing contained in a housing 21, a feed sprocket 22, and this sprocket engages the intermediate portion of a feed chain 23 which passes over idler sprockets 24 and 25 suitably journaled on the support-ing frame. The chain extends forwardly and rearwardly from the idler sprockets longitudinally of the supporting frame and passes around a rear idler sprocket 26 journaled on the rear transverse frame 3 and around a front idler roller 27 journaled on an adjustable bracket 28. The bracket 28 may be adjustable in a conventional manner by a screw and nut device 29 to vary the tension of the feed chain. The feed chain is attached to its ends at 36 to the rear side of the motor casing and at 31 to the forward. side of the cross frame 6, as shown in Fig. 2, so that. when the motor 29 is operated the auger drill steel and its driving motor which constitute the drilling tool may be fed longitudinally along the parallel guides 2 in either of opposite directions. Evidently, the structure of the drill in which the present invention is embodied may assume various other forms.

In a coal drilling tool of the type disclosed it has been found that during operation of the drill, particularly when the latter is in retracted position on the guide frame,

- that the drilling implement due to its substantial length tends at its intermediate portion to vibrate laterally or Whip and to obviate this, an intermediate cross guide or centralizer 35 is slidably guided on the parallel guides 2 between the sliding cross frame 6 and the front transverse frame 4, as shown in Fig. l, and this cross guide or centralizer carries a bushing 36 through which the auger drill steel extends and this brushing embraces and guides the intermediate portion of thedrill steel, andcoacts with the front guide bushing or centralizer to maintain the auger steel centered during its operation.

As the drilling tool is fed forwardly along its guides by the feed sprocket and chain, a projection 37 secured to the cross frame 6 engagesthe rear surface of the inter mediate centralizer or guide 35 and-as the drilling tool continues to advance, shoves the centralized forwardly with the drilling tool along the parallel guides 2 until the intermediate centralizer is in adjacency to or abuts the rear surface of the front transverse frame 4 thereby to limit further forward movement of the drilling tool, as shown in Fig. 3. The feeding motor it? may then be reversed and the drilling tool is retracted by the i sprocket and chain rearwardly along the parallel guides f, and when the drilling tool assumes the position shown in Fig. 4 projections 38, herein desirably in the form of special chain links projecting laterally from the sides of the feed chain (Fig. 6), engage spaced lugs 39 depent 1g from the centralizer frame and straddling the feed c1 in (Fig. so that as the drilling tool is further retracted along the guide frame the intermediate centralizcr is moved rcarwardly along the parallel guides 2 by the feed chain until it assumes the initial retracted position shown in Fig. 2.

As a result of this invention an improved drilling apparatus provided having an elongated driliingimpiemcut and embodying an improved intermediate ccntralizer for the drilling implement to reduce lateral vibration or whip ping of the latter during the drilling operation. By asso ciating the intermediate centralizer with an element of the fe means for the drill, the intermediate centralizer is automatically retracted from its forward position on the guide frame when the feeding means is reversed to effect reverse feed of the drill tool thereby eliminating the need for manual repositioning of the cen tralizer. 3y arranging the intermediate drill steel centralizer so that it is shoved forwardly by the drilling tool as the latter is advanced, and is moved rearwardly by the drill feeding means asthe drilling tool is retracted, the centralizer always is'located in its most eilicient guiding position with respect to the drill steel. The improved intermediate centralizer and its moving means are simple and reliable in design, and may be applied to a conventional drilling apparatus with but little change. Other advantages of the invention will be clearly apparent to those skilled in the art.

While there is in this application specifically described one form which the invention may assume in practice, it will be understood that this form of the same is shown for purposes of illustration and that the invention may be modified and embodied in various other forms without departing 'rom its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a drilling apparatus, an elongated guide, a drilling tool mounted on said guide for movement back and forth therealong, said tool actuating an elongated drilling implement, a centralizer at the front end of said guide for guiding the forward portion of said drilling implement during starting of a hole, an intermediate centralizer mounted on said guide between said tool and said front centralizer and movable back and forth along said guide, feeding means on said guide and operatively connected to said tool for moving the latter back and forth along said guide, said tool as it is advanced engaging said intermediate centralizer to move the latter forwardly there with along said guide until said intermediate centralizer is in adjacency to said frontcentralizer, said tool when said feeding means is reversed moving rearwardly along said guide relative to said forwardly located centralizer, and means providedby said feeding means and engaging said intermediate centralizer when said tool has moved rearwardly a predetermined distance along said guide for retracting said intermediate centralizer to its initial rearward position on said guide.

2. A drilling apparatus as set forth in claim 1 wherein said feeding means for said tool comprises a flexible feeding element guided for circulation relative to said guide and operatively connected to said drilling tool, and said means provided by said feeding means for retracting said intermediate centralizer comprising a projection on said flexible element engageable with a projection on said intermediate centralizer.

3. A drilling apparatus as set forth in claim 2 wherein saidprojection on said flexible element engages said projection 011 said intermediate centralizer only when said tool has moved rearwardly a predetermined distance along said guide, and said projection on said flexible element moving away from said projection on said intermediate centralizer as said tool is fed'forwardly along said guide by said feeding means.

4. A'drilling apparatus as set forth in claim 2 wherein said flexible feeding element consists of a feed chain and said feeding means includes a drive sprocket engaging.

said chain for driving the latter, and said projection on said flexible element is provided by lateral enlargements at the sides of said chain, and said projection on said centralizer havingportions straddling said chain and engaged by said lateraltenlargements as said tool is fed rearwardly by said feeding means.

5. In a drilling apparatus, an elongated guide, a drilling tool movable back and forth along said guide and adapted toJactuate an elongated drilling implement, means for feeding said tool back and forth along said guide, a centralizer for said drilling implement movable back and forth along said guide, and means associated with an element of said feeding means and engaging said centralizer for moving the latter rearwardly along said guide, said centralizer being moved forwardly along said guide by said feeding means, and said means associated with an element of said feeding means engaging said centralizer only after said tool has been moved rearwardly along said guide a predetermined distance relative to said centralizer, and wherein said tool at its front end directly engages said centralizer to shove the latter forwardly along said guide as said tool is advanced and said feeding means has guide a predetermined distance relative to said centralizer, for moving the latter rearwardly only after said tool has been retracteda predetermined'distance' along said guide.

6. An apparatus as set forth in claim 5 wherein said feeding means includes a feeding element movable relative to saidguide during the feeding operation and said means associated with said feeding means comprises an abutment element movable with said feeding element whereby when said feeding element has moved to effect partial retraction of said tool said abutment element engages said centralizer to effect rearward movement of the latter along said guide.

7. In adrilling apparatus, an elongated guide, a drilling tool mounted on said guide for movement back and forth therealong, said tool actuating an elongated drilling implement, a centralizer for said drilling implement also mounted on said guide for movement back and forth therealong, said centralizer disposed in advance of the front end of said tool and engaged and moved forwardly by said tool as the latter is moved forwardly along said guide, means for feeding said tool back and forth along said guide, said'tool moving away from said centralizer as said tool is fed rearwardly, and means operatively associated with said feeding means and actuated thereby for retracting said centralizer; from a forward position along said guide frame as said tool and theimplement actuated thereby are fed rearwardly, said retracting means comprising an element engaging said centralizer as said tool is fed rearwardly.

References Cited in the file of this patent UNITED STATES PATENTS 

